1. Field of the Invention
The present invention generally relates to chemical processes and more particularly to packings in columns.
2. Description of the Related Art
Column packing is used in the chemical, environmental, and petrochemical industries. The packing elements are generally used to enhance chemical reaction throughput. Such column packing are generally divided into three classes, namely:                a) Random or dumped packing: These are discrete pieces of packing of a specific geometrical shape, which are dumped or randomly packed into the column shell.        b) Structured or systematically arranged packing: These are crimped layers of wire mesh or corrugated sheets. Sections of these packing are stacked in the column.        c) Grids: These are also systematically arranged packing, but instead of wire-mesh or corrugated sheets, these grid-packings use an open-lattice structure.        
There are three generations of evolution in packing. An overview of the three generations of developments packing is provided in the related application Ser. No. 10/231,500.
One of the continuing challenge for improving the known art of packing design involves increasing the total available surface areas of the packing elements while maintaining the structural strength and improving fluid flow.
By increasing the surface area of packing, more liquid loading (in terms of gallons per minute per square feet) can be achieved, which in return can improve the reaction efficiency at the wetting surface of, for example, gas stream and liquid feed stream, as in the example of toxic gas scrubber process, or for liquid feed streams in a distillation column operation. However, increasing the surface area typically leads to increased resistance to the fluid flow which in turn decreases the throughput. On the other hand, cutting materials from the packing may increase the fluid flow but may reduce the structural strength of the packing, which may cause collapse of the elements and necessitate their replacement. Thus, design of the packing elements presents interesting mathematical challenges of competing problems of providing maximum contact area to improve reaction rates, maintain structural strength, and improve fluid flow.
In order to increase the surface area, the packing elements become more complex in geometrical shapes, resulting in more individual breakage, less structural rigidity, and more interlocking inside a CPI column. Thus, the challenge facing packing element technology is how to significantly increase the surface area without sacrificing the structural integrity of the individual packing.
The engineers persistently encounter the problem of carving out more space (for increased throughput) to produce more surface area (for increased reaction surface) from materials like metals or plastics because the operation will always weaken structural integrity. The more complex the geometrical shapes, the more surface area, and the damage to the structural integrity of the packing.
Therefore, it would be highly desirable to design geometrical shapes, which not only maximize reactants surface contact area, maintain structural integrity of the structure but also minimize pressure drop to enhance the throughput of the apparatus. It is also desirable to design geometries that would prevent nesting by eliminating sharp protrusions that may be damaged in loading the apparatus. Yet another desirable characteristic would be to design the geometry that would provide easy removal of the packing from tower columns for periodic cleaning. Still another desirable characteristic would be easy element assembly to sufficiently reduce assembly time and reduce corresponding cost